Abstract
While oral desensitization is capable of alleviating peanut allergen anaphylaxis, long-term immune tolerance is the sought-after goal. We developed a liver-targeting lipid nanoparticle (LNP) platform to deliver mRNA-encoded peanut allergen epitopes to liver sinusoidal endothelial cells (LSECs), which function as robust tolerogenic antigen-presenting cells that induce FoxP3+ regulatory T-cells (Tregs). The mRNA strand was constructed by including nucleotide sequences encoding for nonallergenic MHC-II binding T-cell epitopes, identified in the dominant peanut allergen, Ara h2. These epitopes were inserted in the mRNA strand downstream of an MHC-II targeting sequence, further endowed in vitro with 5' and 3' capping sequences, a PolyA tail, and uridine substitution. Codon-optimized mRNA was used for microfluidics synthesis of LNPs with an ionizable cationic lipid, also decorated with a lipid-anchored mannose ligand for LSEC targeting. Biodistribution to the liver was confirmed by in vivo imaging, while ELISpot assays demonstrated an increase in IL-10-producing Tregs in the spleen. Prophylactic administration of tandem-repeat or a combination of encapsulated Ara h2 epitopes induced robust tolerogenic effects in C3H/HeJ mice, sensitized to and subsequently challenged with crude peanut allergen extract. In addition to alleviating physical manifestations of anaphylaxis, there was suppression of Th2-mediated cytokine production, IgE synthesis, and mast cell release, accompanied by increased IL-10 and TGF-β production in the peritoneum. Similar efficacy was demonstrated during LNP administration postsensitization. While nondecorated particles had lesser but significant effects, PolyA/LNP-Man lacked protective effects. These results demonstrate an exciting application of mRNA/LNP for treatment of food allergen anaphylaxis, with the promise to be widely applicable to the allergy field.